1. Field of the Invention
The present invention relates generally to the medical and surgical fields, and more specifically to an internal prosthesis (endoprosthesis) for the shoulder joint between the acromion extension of the scapula and the outward end of the clavicle. The acromioclavicular joint prosthesis of the present invention serves to reconnect the two bones of this joint, while providing the freedom of movement and shock absorption required.
2. Description of the Related Art
Shoulder injuries occur relatively frequently, and may comprise injury to any of a number of different joints and tissues. While a relatively simple dislocation of the ball of the upper arm bone (humerus) from its glenoid seat in the scapula is perhaps the most common shoulder injury, there are a large number of other injuries which can occur, from breakage of bones in the shoulder area to the tearing of ligaments and other tissues, damage to the joints due to arthritis or other osteal deterioration, etc. In many cases, the shoulder joint is damaged to the extent that it is no longer capable of functioning to anywhere near a normal extent.
As a result, a number of artificial shoulder joints have been developed in the past, as evidenced by the number of earlier patents for such devices. However, none of those devices provide for the repair of a separation between the distal (outward) end of the clavicle and the acromion, which extends outwardly from the scapula. This joint serves to hold the shoulder up in its normal position, among other purposes. When this joint separates, the scapula and its attached humerus tend to drop downwardly and outwardly, as there is no other bone joint connecting the scapula to the remainder of the skeletal structure. At least some form of external support is required for even limited function of the affected joint and limb, with surgical repair being desired.
However, surgical repair does not always prove effective. In many instances, the repaired joint separates again, reverting to the same problem as before the surgery was done. Yet, to the knowledge of the present inventor, no one has developed any form of artificial or prosthetic joint that may be substituted for the damaged acromioclavicular joint for forming a durable repair.
Accordingly, the present invention provides a solution to this problem in the form of an acromioclavicular joint prosthesis which may be used to provide a secure and durable repair to a damaged acromioclavicular shoulder joint. The present prosthesis essentially comprises an acromion attachment component and a clavicle attachment component, with appropriate connection elements therebetween to provide the required freedom of movement for the joint. Means for securing the two attachment components to their respective bones, is also provided.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 3,869,730 issued on Mar 11, 1975 to Barry A. Skobel, titled “Surgically Implantable Joint Prosthesis,” describes an artificial joint for replacing the shoulder attachment ball of the humerus and its scapular glenoid socket. The prosthetic joint includes a gimbal to provide the necessary degrees of freedom for the joint, as well as perforations to provide for bone ingrowth for more secure attachment as the repair heals. However, the Skobel prosthetic device does nothing to provide for the reattachment of a separated acromioclavicular joint and does not provide a prosthetic joint structure for this joint, as provided by the present invention.
U.S. Pat. No. 3,979,778 issued on Sep. 14, 1976 to Jerome H. Stroot, titled “Shoulder Prosthesis,” describes another artificial replacement for the humerus and scapula glenoid joint. Again, no disclosure is made of any form of prosthetic joint for the acromion and clavicle, as addressed by the present invention.
U.S. Pat. No. 4,550,450 issued on Nov. 5, 1985 to James G. Kinnett, titled “Total Shoulder Prosthesis System,” describes both a humerus—scapula joint prosthesis and a prosthesis secured to the acromion, with the artificial ball of the humerus bearing against the acromion prosthetic component. However, the acromion component is a relatively simple plain bearing pad against which the upper portion of the joint ball of the humerus bears. Kinnett appears to indicate that the distal or outer end of the clavicle would be immovably affixed to the acromion by means of his acromion prosthesis, which would greatly limit certain motions of the shoulder. Kinnett does not disclose any form of articulated joint between the clavicle and acromion extension of the scapula, as provided by the present acromioclavicular joint prosthesis.
U.S. Pat. No. 5,944,757 issued on Aug. 31, 1999 to Paul M. Grammont, titled “Total Trochitero-Acromial Shoulder Prosthesis,” describes a shoulder joint prosthesis comprising an artificial ball for attachment to the shoulder joint end of the humerus and a plain bearing for attachment to the lower surface of the acromion, against which the ball of the humerus bears. However, Grammont fails to provide any form of attachment between the acromion and the clavicle. The present acromioclavicular joint prosthesis provides for an articulated connection between these two skeletal components.
U.S. Pat. No. 6,132,467 issued on Oct. 17, 2000 to Arnold Keller, titled “Endoprosthesis, In Particular For The Sternoclavicular Joint,” describes a prosthetic joint configured for installation in a joint where the two bones cannot be easily distracted (separated) from one another. One such joint is the inner end of the clavicle and its connection to the sternum, which is the opposite end of the clavicle from the end to which the present acromioclavicular prosthesis is secured. While Keller does provide a ball joint, he does not disclose the means for positively attaching the two bones together, particularly the acromion and scapula, as provided by the present invention.
U.S. Pat. No. 6,193,758 issued on Feb. 27, 2001 to Randall J. Huebner, titled “Shoulder Prosthesis,” describes a replacement for the shoulder contact ball of the humerus. The Huebner prosthesis includes an extension which is driven into the medullar (marrow) canal of the humerus, to secure the joint ball in place. However, Huebner does not disclose any form of joint prosthesis for connecting the acromion and clavicle together, as provided by the present invention.
U.S. Pat. No. 6,620,197 issued on Sep. 16, 2003 to Brian J. Maroney et al., titled “Method And Apparatus For Performing A Shoulder Replacement Procedure In The Treatment Of Cuff Tear Arthropathy,” describes a prosthetic humerus ball joint, similar to the Huebner device discussed immediately above. The major difference between the Huebner and Maroney et al. prostheses is that Maroney et al. provide a spherical ball surface of more than 180 degrees of spherical arc. However, no prosthetic acromioclavicular joint is disclosed by Maroney et al.
U.S. patent Publication No. 2002/99,381 published on Jul. 25, 2002, titled “Method And Apparatus For Resecting A Greater Tubercule From A Humerus Of A Patient During Performance Of A Shoulder Replacement Procedure,” describes a tool and method for removing the protuberance of bone from the humerus which is adjacent the ball end thereof. This tool and method would be used during the operation for installing the prosthetic ball described in the '197 U.S. patent to Maroney et al., described immediately above. No acromioclavicular joint prosthesis is disclosed in the '381 patent Publication.
U.S. patent Publication No. 2002/99,445 published on Jul. 25, 2002, titled “Method And Apparatus For Performing A Shoulder Replacement Procedure In The Treatment Of Cuff Tear Arthropathy,” is the earlier publication of the U.S. patent application which resulted in the issuance of the '197 U.S. patent to Maroney et al. on Sep. 16, 2003, discussed further above. The same points of difference between the device of the Maroney et al. '197 U.S. patent and the present invention noted in that discussion, are seen to apply here as well.
U.S. patent Publication No. 2003/144,738 published on Jul. 31, 2003, titled “Acromial-Humeral Prosthesis And Method Of Implantation,” describes a two piece bearing which is affixed to the underside of the acromion extension of the scapula, and which serves as a plain bearing surface for the upper portion of the ball of the humerus. However, the '738 publication does not disclose any form of connection between the acromion and the clavicle, which connection is addressed by the present prosthetic joint invention.
U.S. Design Pat. No. 285,969 issued on Sep. 30, 1986 to James G. Kinnett, titled “Acromial Prosthesis Component For Total Shoulder Prosthesis System,” illustrates a design for the acromion attachment bearing described in the '450 U.S. Utility patent to the same inventor, discussed further above. As in the case of his '450 U.S. Utility patent, no acromioclavicular prosthetic joint is disclosed by Kinnett in his '969 U.S. Design patent.
French Patent Publication No. 2,541,890 published on Sep. 7, 1984, titled “Total Shoulder Prosthesis,” describes (according to the drawings and English abstract) a prosthetic humerus ball joint replacement and a prosthetic replacement for the glenoid socket of the scapula. The glenoid replacement also attaches beneath the acromion, but no acromioclavicular joint prosthesis is disclosed in the '890 French Patent Publication. While the inventor named in the '890 French patent is also the inventor of record in the '757 U.S. patent discussed above, it should be noted that the inventions described in the '757 U.S. patent and the '890 French Patent Publication are different from one another.
Finally, PCT Patent Publication No. WO 93/09733 published on May 27, 1993, titled “Modular Prosthesis,” describes a series of components for a modular humerus ball joint prosthesis. The assembly is quite similar to that disclosed in the Huebner '758 and Maroney et al. '197 U.S. patents and the Maroney et al. '445 U.S. patent Publication. The same points of difference noted further above in the discussion of the '758 Huebner and '197 Maroney et al. U.S. patents and the Maroney et al. '445 U.S. patent Publication are seen to apply here as well, i.e. no acromioclavicular joint prosthesis is disclosed in those patents and patent publication.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus an acromioclavicular joint prosthesis solving the aforementioned problems is desired.